Luminaires with automated and remotely controllable functionality are well known in the entertainment and architectural lighting markets. Such products are commonly used in theatres, television studios, concerts, theme parks, night clubs and other venues. A typical product will commonly provide control over the pan and tilt functions of the luminaire allowing the operator to control the direction the luminaire is pointing and thus the position of the light beam on the stage or in the studio. Typically this position control is done via control of the luminaire's position in two orthogonal rotational axes usually referred to as pan and tilt. Many products provide control over other parameters such as the intensity, color, focus, beam size, beam shape and beam pattern. The beam pattern is often provided by a stencil or slide called a gobo which may be a steel, aluminum or etched glass pattern. The products manufactured by Robe Lighting such as the Robin 300E Spot are typical of the art.
The optical systems of such luminaires may include a gate or aperture through which the light is constrained to pass. Mounted in or near this gate may be devices such as gobos, patterns, irises, color filters or other beam modifying devices as known in the art. The use of a framing shutter system at this point allows control over the size and shape of the output beam and thus the size and shape of the image projected onto a surface.
FIG. 1 illustrates a multiparameter automated luminaire system 10. These systems commonly include a plurality of multiparameter automated luminaires 12 which typically each contain on-board a light source (not shown), light modulation devices, electric motors coupled to mechanical drives systems and control electronics (not shown). In addition to being connected to mains power either directly or through a power distribution system (not shown), each luminaire is connected is series or in parallel to data link 14 to one or more control desks 15. The luminaire system 10 is typically controlled by an operator through the control desk 15.
FIG. 2 illustrates an automated luminaire 12 incorporating the improved shutter system 25. A lamp 21 contains a light source 22 which emits light which may have a power supply 27. The light is reflected and controlled by reflector 20 through color system 23 which may include dichroic color mixing and color wheels, an aperture or imaging gate 24 and then through a framing shutter system 25. The resultant light beam may be further constrained, shaped, colored and filtered by optical devices 26 which may include dichroic color filters, gobos, rotating gobos, variable aperture iris, effects glass and other optical devices well known in the art. The final output beam may be transmitted through output lenses 28 and 31 which may form a zoom lens system.
Framing shutter system 25 is most commonly constructed as a plurality of metal plates or blades that may be individually and separately inserted across the light beam to mask a portion of that beam. Each blade may be completely removed from the light beam or may be adjusted to occlude a portion of the light beam. It is possible to use any number of blades; however it is common to utilize four allowing framing the projected image to common rectangular shapes such as picture frames. It is also well known to provide individual angular control for each blade such that the four blades do not have to remain at fixed, perpendicular, angle to each other and thus irregular trapezoidal or triangular shapes may be formed by combinations of the blades.
The prior art contains various examples of such framing shutter systems, for example U.S. Pat. No. 1,793,945 illustrates a four blade system where each blade may be manually adjusted to cover a portion of the light beam. This system does not provide beam rotation. U.S. Pat. No. 4,890,208 to Izenour discloses a further four blade system where each blade is provided with two motors such that both the position and angle of each blade can be remotely adjusted. US Patent Application 2005/02319578 to Wynne-Willson discloses a yet further system where each blade can be remotely adjusted for position and rotation and may also be rotated around the beam. Wynne-Willson further discloses that each blade may have two selectable edges which may be optionally inserted across the beam. He illustrates this as a straight edge or a curved edge. This offers some advantage to the user as shapes other than straight sided polygons can be framed, however the system disclosed is a very complex mechanism which would be expensive and difficult to manufacture. Further mechanisms are disclosed in U.S. Pat. No. 6,550,939, U.S. Pat. No. 6,744,693, U.S. Pat. No. 6,939,026, European patent EP 1428070, patent application WO 96/26384 and UK Patent GB2270969. All of these mechanisms offer some means for framing at least two sides of a light beam and may also provide position and rotation of each blade however the described mechanisms are either slow to operate, such as EP1428070 or one embodiment of WO 96/26384 which rely upon a lead screw system, or have many interconnected parts which lead to inaccuracies from tolerances in the system.
There is a need for an improved automated framing shutter mechanism for an automated luminaire which provides the user with both accurate positioning and the ability for rapid movement.